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Polylysine-induced rapid Ca2+ release from cardiac sarcoplasmic reticulum
1Second Department of Internal Medicine, Yamaguchi University School of Medicine, Ube, Japan.
Journal of Cardiovascular Pharmacology
|July 24, 1998
Summary
Polylysine rapidly triggers calcium release from cardiac sarcoplasmic reticulum (SR) and influences ryanodine binding. Cardiac SR shows a distinct polylysine concentration dependence compared to skeletal SR.
Area of Science:
- Cardiovascular Physiology
- Molecular Biology
- Cellular Physiology
Background:
- Cardiac sarcoplasmic reticulum (SR) is crucial for regulating intracellular calcium (Ca2+) levels during heart muscle contraction.
- Understanding the mechanisms of Ca2+ release from the SR is vital for comprehending cardiac function and dysfunction.
Purpose of the Study:
- To investigate the rapid kinetics of polylysine-induced Ca2+ release from cardiac SR.
- To assess the effect of polylysine on ryanodine binding to cardiac SR.
- To compare the concentration-dependent activation of cardiac and skeletal SR Ca2+ release channels by polylysine.
Main Methods:
- Isolation of SR vesicles from canine cardiac muscle.
- Continuous monitoring of SR Ca2+ release using a stopped-flow apparatus.
- Measurement of [3H]ryanodine binding via filtration assays.
Main Results:
- Polylysine induced rapid Ca2+ release from cardiac SR.
- Cardiac SR exhibited a unique concentration dependence for polylysine-induced Ca2+ release, increasing up to 3.7 microM.
- Polylysine also stimulated [3H]ryanodine binding, mirroring the Ca2+ release kinetics.
- Distinct concentration-dependent differences were observed between cardiac and skeletal SR activation by polylysine.
Conclusions:
- The cardiac SR Ca2+ release channel is sensitive to polylysine activation.
- Significant differences exist in the polylysine concentration dependence of Ca2+ release channel activation between cardiac and skeletal muscle SR.